What is an RDE2 diesel?
When a new car is certified for sale in the UK and Europe, it must undergo strict emissions testing. Current standards state that, under standard laboratory testing, a new diesel or petrol car must emit no more than 0.080g/km of nitrogen oxide (NOx).
RDE stands for Real Driving Emissions. This is the test that can be used by vehicle manufacturers to test the emissions a car produces under real driving conditions (e.g. not in a laboratory).
RDE was introduced in September 2017 and, at the moment, OEMs have the option of putting new cars through the test, in addition to the standard laboratory emissions test. It will not be mandatory for all new cars to be put through RDE until September 2019.
However, because there is an expected difference between emissions from a car in the laboratory and under real world testing, there are different stages of RDE.
The first stage allows a car to emit 2.1 times the amount of NOx during RDE testing.
The second stage, RDE2, allows cars to emit 1.5 times the amount of NOx during RDE testing. This becomes mandatory for all cars on sale by January 2021.